I sometimes feel I know Alan Bennett's family almost as well as my own. But, although these two "recollections" contain material that will be familiar to readers of Bennett's memoirs Untold Stories, they make a surprisingly rich theatrical event: they not only convey his peculiar ironic-elegiac tone, but, through their vivid particularity, stir your recollections of adolescence.

Hymn, though running at only half an hour, is the more memorable: an exquisite prose-poem, spoken to music written or arranged by George Fenton and played by members of Southbank Sinfonia, about a particular moment in Bennett's childhood when his father tried to teach him the violin. His father was an enthusiastic musician who played along to the Palm Court orchestra on the radio, but his gift was not transmitted to his 10-year-old son; there comes a heartrending moment when the young Bennett realises that his father's disappointment "will outlast the violin and my childhood, and go down to the grave".

Far from being an extended anecdote, the piece awakens our memories of youthful failure. It is also beautifully written: recollecting two famous conductors he heard at Leeds Town Hall, Bennett observes that "it is Barbirolli who touches the heart and serves the music, unlike Sargent who merely presents it". Alex Jennings plays Bennett to perfection: with his blond fringe and flat vowels, he not only looks and sounds like the original, but also, in the way he surveys the on-stage quartet with an appreciative envy, conveys the solitude of the compulsive non-joiner.

Jennings is back as Bennett in the hour-long Cocktail Sticks, in which the middle-aged writer regrets the uneventful ordinariness of his Leeds childhood, only to realise belatedly that the apparently mundane contains its own mystery. The focus here is mainly on Bennett's mum, marvellously incarnated by Gabrielle Lloyd, and her social aspirations and later mental illness: Bennett's rueful affection is precisely caught in his observation that his mother felt depression was something reserved for the privileged and "an affliction to which she was not socially entitled".

Even if much of the material is not new, it gains by being staged in Nicholas Hytner's economical production and by being filtered through the prism of Jennings's performance. The piece also confirms my thesis that Bennett is not quite the cosy writer he is often taken to be. The prevailing emotion in Cocktail Sticks is one of profound guilt: Bennett's guilt at his slowness to realise that anything can be the stuff of literature, and the scholarship-boy's guilt at feeling embarrassed by his parents. In his remorseless excavation of his past, Bennett opens up all our yesterdays.